The protein, cytochrome c551 which was extracted from Pseudomonas aeruginosa is being studied by 13C NMR spectroscopy as a function of pH, oxidation state, and temperature. The kinetics of proton and electron transfer from a companion protein, azurin are also being investigated. An attempt is being made by proton NMR studies of rare earth derivatives of transferrin to identify the ligands at each of the two metal binding sites; recent findings that trypsin splits bovine transferrin into two fragments, each containing one metal binding site are being exploited. Electrons will be photochemically generated in solution and their reaction with protein disulfide bonds will be followed as a function of time.